Oxidation process using peracetic acid



United States Patent 3,278,562 UXKDATHQN PROCESS USHNG PERACETHC ACID Hubert H. Thigpen, Wallace E. Taylor, and Arthur W. Schnizer, Corpus Christi, Tern, assignors to Celanese Corporation of America, New York, N.Y., a corporation of Delaware No Drawing. Filed Aug. 30, 1962, Ser. No. 220,553 Claims. (Cl. 260-3485) This invention relates to the use of peracetic acid as an agent for the addition of oxygen to various organic compounds.

It has been known for a great many years that acetaldehyde can be oxidized in the vapor phase with oxygen to peracetic acid. Solutions of peracetic acid in an inert solvent are commercial products which have been used as oxidizing or epoxidizing agents to epoxidize olefins as well as to manufacture other useful products.

An article recently published in Great Britain by John et al., Chemistry and Industry, January 17, 1962, page 62 if, contains a good summary of work which has been done in this field both in the preparation and utilization of peracetic acid. This article shows that peracetic acid can be made by reaction of hydrogen peroxide and acetic acid; liquid phase oxidation of acetaldehyde to acetaldehyde monoperacetate in an inert diluent followed by decomposition of the monoperacetate while still in solution in inert diluent; and vapor phase oxidation of acetaldehyde to peracetic acid followed by recovery of the peracetic acid in inert solution by vacuum distillation in the presence of benzene.

John et al. relate that it is very diflicult to isolate the products of vapor phase oxidation of acetaldehyde but that they have accomplished this by extractive distilling in a column containing an inert diluent which column has carefully chosen reaction conditions, e.g. a base temperature less than about 80 C. The recovered product is a 25% peracetic acid solution in the inert diluent. This article goes on to state that peracetic acid had been principally regarded as an hydroxylating agent until it was dis covered that epoxidations could be accomplished by the use of peracetic acid in inert solution. Still later Swern et al. in the Journal of the American Chemical Society and in several patents showed that peracetic acid in acetic acid solution was a good epoxidizing agent.

Thus, it is seen that it has been the practice in the past to manufacture peracetic acid, by whatever method is convenient; recover the thus made peroxy acid in inert solution; either store it or sell it in solution; and then utilize the thus available per acid solution as an oxidizing or epoxidizin-g agent in an appropriate chemical reaction.

It has now been discovered that oxidations or epoxidations can be effected utilizing as the oxidizing agent vapors containing peracetic acid and acetaldehyde. An eminently well suited source of such vapors is the product of vapor phase oxidation of acetaldehyde. This discovery makes it practical to utilize peracetic acid as an oxidizing or epoxidizing agent directly as made.

It is an object of this invention to oxidize or epoxidize by introducing the peracetic acid oxidizing or epoxidizing agent as a vapor. It is another object of this invention to provide a series of novel chemical syntheses based upon the utilization of peracetic acid produced by the vapor phase oxidation of acetaldehyde. It is a further object of this invention to utilize the product of vapor phase oxidation of acetaldehyde directly in various oxidation or epoxidation reactions without the necessity of co lection, purification or isolation of the peracetic acid content thereof. It is a still further object of this invention to carry out the oxidation reactions herein described in a novel reactor. Other and additional objects will become apparent from a consideration of this entire specification.

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In accord with and fulfilling these objects, this invention includes as one of its aspects, a process which comprises carrying out oxidation or epoxida-tion reactions utilizing a vapor containing peracetic acid as the oxidizing or epoxidizing agent. In this connection it is preferred to utilize a vapor comprising peracetic acid in admixture with a diluent which is at least inert in the vapor phase.

Where the peracetic acid containing vapor is the reaction product of vapor phase oxidation of acetaldehyde, the vapor contains as a diluent at least acetaldehyde. It is indeed surprising that even though acetaldehyde and peracetic acid react together quite readily in the liquid phase, there is substantially no reaction between these compounds in the vapor phase. It is also quite surprising that peracetic acid will selectively oxidize or epoxidize other compounds in the process of this invention without reacting to any substantial extent with acetaldehyde. This vapor is contacted with an appropriate compound directly and without the necessity of further purification, isolation or condensation to isolate peracetic acid therefrom and upon contact the peracetic acid is absorbed in the compound and oxidizes, epoxidizes or in some other way adds oxygen to the compound thereby forming an oxygenated product. The oxidation product also includes acetic acid, which is the reduced form of peracetic acid, in addition to the oxygenated derivative or derivatives. This oxidation product can be recovered and/ or separated as desired.

As stated above, a particularly good source of a vapor containing peracetic acid is the oxidation product of the vapor phase oxidation of acetaldehyde. This vapor comprises acetaldehyde and peracetic acid. When this vapor is utilized to oxidize or epoxidize a compound, the reaction product is acetic acid, unreacted compound and one or more oxygen addition products of said compound, as well as acetaldehyde which generally passe through the reaction environment substantially unreacted. This product is suitably separated into its valuable components with the acetaldehyde preferably being recycled to the oxygen oxidation reaction and the acetic acid being recovered as a valuable, salable product. It is of course intended that this invention shall not be limited to dispos ing of this product in the manner set forth above. This is the preferred disposition of products. If desired, any one or more fractions of this reaction product may be considered waste and disposed of accordingly. Any other alternative disposition may similarly be employed as desired.

According to this invention, the vapor phase oxidation of acetaldehyde to a vaporous oxidation product comprising peracetic acid in admixture with acetaldehyde can be accomplished by following the teachings of the John et al. article referred to above or the teachings of US. Patent 2,314,385, Bludworth. In accord with this invention, however, the oxidized reaction mixture of the Bludworth patent or similar vapor streams comprising peracetic acid are not necessarily fractionated to isolate peracetic acid as set forth in Bludworth, but rather this reaction mass, which is the oxidation product referred to above, is directly utilized in the steps of the instant process which follow. This reaction mass comprises, as set forth above, acetaldehyde and peracetic acid and it is most surprising that in the vapor phase these two compounds do not react to any appreciable extent to form acetic acid. This vaporous reaction mass may, and often does, contain acetic acid and may in some cases contain some unreacted oxygen or inert gasses such as nitrogen.

Acetaldehyde oxidation in the vapor phase with oxygen can be carried out under a wide range of reaction conditions. Best results are obtained at temperatures of about C. and higher, preferably about C. to C. Also, it is preferred for best results, though not essential,

to operate substantially isothermally at any given selected operating temperature. The operating pressure should be atmospheric or higher, pressures of about 15 to 30 p.s.i.g. being preferred. Oxygen conversion should preferably be less than 100% in order to reduce the possibility of degradative oxidation. Exceptionally fine results have been attained when an oxygen conversion of about 85 to 95% is permitted. Contact times of vaporous acetaldehyde with oxygen up to about 46 seconds have been employed which resulted in conversion efiiciencies of acetaldehyde to desired products of about 95 to 100 percent. It is preferred to permit contact times of at least about 5 seconds. The oxidizing oxygen may be diluted with inert materials if desired.

It is also preferred to utilize a vapor phase oxidation reactor which has an inert surface. In this respect, United States Patent No. 3,192,256, assigned to the assignee hereof, can be considered as suitably defining reactor materials which are inert with respect to this reaction. For example, aluminum and polytetrafluoroethylene are specific materials which do not inhibit the oxidation of acetaldehyde to peracetic acid in the vapor phase, catalyze side reactions of acetaldehyde with oxygen or encourage decomposition of peracetic acid when made. In this connection, it is also preferred to provide low surface to volume ratios in the oxidation reactor in which peracetic acid is made for use in this invention.

It has been found that a particular set of operating conditions is optimum for the vapor phase oxidation of acetaldehyde to a peracetic acid product stream for use in this invention: temperature 130 to 160 C.; pressure to 30 p.s.i.g.; oxygen concentration in feed 9 mole percent; nitrogen (inert) dilution up to oxygen conversion 85 to less than 100%; contact time 8 to 40 seconds; reactor surface to volume ratio at most 0.5 per centimeter; and reactor constructed of aluminum.

According to this invention, the vapor phase oxidation product including unreacted acetaldehyde leaving the vapor phase acetaldehyde oxidation reactor is suitably fed, still in the vapor phase, into contact with an organic chemical to be oxidized or epoxidized. The product of the reaction which takes place between the acetaldehyde oxidation product and the organic chemical is preferably collected or directly separated into its components and at least the oxidized or epoxidized product recovered. This invention is adapted to use for oxidizing or epoxidizing compounds usually subjected to such treatment. Good lists of such compounds are set forth in: an article by Daniel Swern which article was published in Chemical Review 45, l-68 (1948), US. Patent 2,785,185, Phillips et al.; US. Patent 3,002,004, Beavers et al.; US. Patent 2,802,800, Sprules et al., and British Patent No. 811,046.

A particularly important aspect of this invention is the discovery that a distillation column is admirably suited to use as the vessel in which to carry out the reaction of vaporous peracetic acid with the above referred to oxidizable compound while simultaneously separating the reaction product mass into at least two major fractions, a liquid rafiinate and a vaporous distillate. Location of points of reactant feed and product withdrawal from the still-reactor as well as the operating conditions of the still-reactor, including temperatures, pressures, feed rates and column design, are so adjusted that the concentration of peracetic acid decreases upwardly in the column from the feed point; the concentration of acetic acid decreases from the top to the bottom of the column; the concentration of the compound being oxidized or epoxidized decreases from the top to the bottom of the column; the concentration of the oxygenated product increases from the top to the bottom of the column; and there is little or no acetaldehyde in the liquid phase anywhere in the column. By operating a still-reactor in such manner as to accomplish these concentration gradients, the high concentration of the compound being oxidized or epoxidized in the upper sections of the column tends to encourage reaction with peracetic acid and drive this reaction toward completion; and the high concentration of peracetic acid in the lower sections of the column tend to encourage reaction with the compound being oxidized or epoxidized and drive this reaction toward completion. Since acetic acid tends to cause ring opening of oxirane (epoxide) linkages, the combination of low concentration of oxygenated compound and high concentration of acetic acid in the upper sections of the column and the combination of low acetic acid concentration and high concentration of oxygenated compound in the lower sections of the column both tend to inhibit and minimize oxygenated product degradation and loss through ring opening and hydroxylation.

The composition of the railinate and distillate will of course vary to at least some extent with the nature of the compound being reacted. Likewise, the proportions of the components of both the raflinate and the distillate will vary with the reaction conditions and with the proportions of the reactants. It can be stated as a general proposition, however, that the vaporous distillate will be made up of predominantly acetaldehyde, acetic acid and any gases having boiling points lower than acetaldehyde, referred to as permanent gases, which may exist in the reaction mass. The rafiinate will, as a general rule, contain the oxygen addition product of the reaction, unreacted compound, if there is any, possibly some acetic acid, and any oxidative degradation products having a boiling point which is higher than that of acetic acid. For purposes of ease of understanding, the distillate will be further considered as consisting of acetaldehyde and acetic acid and the rafiinate will be considered as consisting of oxidation addition product and any unreacted compound still retained in the system. Each of the distillate and the raflinate can often be further separated into its components. Thus where the compound being oxidized has a boiling point below its decomposition temperature and is adapted to be distilled, the raifinate can be fractionated to recover unreacted compound as a distillate and the oxygen addition product or products thereof as a raffinate. Likewise, the vapors distillate taken from the still-reactor can be subjected to partial condensation whereby acetic acid is condensed and acetaldehyde is retained in the vapor state. Where the product of the still-reactor is thus separated, it is convenient to recycle the vaporous acetadehyde to the vapor phase oxidation of acetaldehyde reactor and to recycle any unreacted oxidizable compound that is recovered to the still-reactor.

The still-reactor in which it is preferred to carry out oxidation or epoxidation reactions according to this invention is conveniently a distillation column which may either have plates or be packed, provided however that the materials of construction and the packing, if there is any, should be substantially inert to the reaction and to the reactants. This column can contain, e.g., about 3 to 60 plates and preferably operates at a temperature of about 60 to C. at a pressure of about 50 mm. Hg absolute to atmospheric. Where a packed column is used, the packing can be Berl saddles, Raschig rings, helipods or other conventional shapes. Materials of construction of a still-reactor for use in this invention include halogenated polyolefins, tin, magnesium, stainless steel, aluminum, pyrex glass, titanium, tantalum and zirconium. Feed rates of peracetic acid vapor to the still-reactor are suitably up to about 1.5 equivalents per equivalent of the compound being oxidized or epoxidized. The absolute feed rate per unit of time is of course dependent upon the size of the equipment in which this process is being carried out. Thus, where compounds are being oxidized or epoxidized which have more than one reactive center, e.g., linolenic acid or cyclopentadiene, the mole ratio of peracetic acid to compound should be based upon the number of reactive centers in the compound, e.g., the mole feed ratio of peracetic acid to cyclopentadiene will be about twice the mole feed ratio of peracetic acid to cyclohexanone.

It will be apparent from the above general discussion that process described herein is eminently suited to continuous operation with acetadehyde and oxygen being fed at one end of the process and oxidizable compound fed at an intermediate point in the process, and acetic acid and oxygen addition compound or compounds of the oxidizable compound or lower homologues thereof taken as the product. While continuous operation is therefore to be preferred, it is also within the scope of this invention to operate the over-all process batchwise, that is, to feed a limited quantity of acetaldehyde, oxygen and oxidizable compound and collect a limited quantity of oxygen addition product acetic acid, acetaldehyde and unreacted oxidizable compound. This invention can also be carried out in a series of kettle type reactors or cascade type reactors.

Alternatively, it is within the scope of this invention to utilize an artificially prepared vapor stream containing peracetic acid as the epoxidizing or oxidizing agent in sufficient proportion to act as intended. Thus, a vapor of predetermined proportions of peracetic acid and a relatively inert diluent, such as acetaldehyde, acetic acid, ace tone, methyl acetate or ethyl acetate, from whatever source, can be conveniently employed in the practice of this invention. Further, the peracetic acid can be prepared by whatever process is conveniently available and used alone or mixed with an inert diluent as desired. This process has a -wide range of variants and has broad applicability. It is preferred to utilize a peracetic acidcontaining vapor, as the oxidizing or epoxidizing medium, which contains about 2 to 35 weight percent peracetic acid, preferably 5 to 20 weight percent. The oxygen oxidation of acetaldehyde to peracetic acid, as well as the utilization of a vapor containing peracetic acid as an oxidizing or epoxidizing agent, have been practiced with excellent results Without the aid of catalysts of any kind. However, it is within the scope of this invention to utilize a catalyst or catalysts at any appropriate point in the process to improve the yields, efiiciencies or both.

The reaction conditions in the still-reactor can be varied within Wide limits depending upon the eificiency and yield of products desired, and depending upon the par ticular compound being oxidized or epoxidized. Thus the temperature can be in the range of about 65 to 150 C. at a pressure of about 50 mm. Hg absolute to atmospheric for a contact time of about 30 seconds to 2 hours. In most embodiments of this invention the reaction conditions are so chosen that substantially all the acetaldehyde that may be in vaporous peracetic-containing feed stream remains uncondensed in the inlet zone of the still-reactor while the peracetic acid portion of the incoming stream is absorbed upon contact thereof with the compound being oxidized or epoxidized whereupon the compound and peracetic acid react.

Representative groups of compounds which are adapted to be oxidized or epoxidized according to this invention are those having boiling points higher than acetaldehyde and generally include: (1) ketones; (2) diketones; (3) aldehydes; (4) aromatics; (5) acetylenes; (6) phosphites; (7) sulfides; (8) amines; and (9) olefinic compounds. The products of oxidizing or epoxidizing compounds of these representative groups are respectively: (1) esters; (2) carboxylic acids and anhydrides or alcohols and pyruvic acid derivatives; (3) carboxylic acids; (4) dicarboxylic acids and quinone derivatives; (5) unsaturated ketones; (6) phosphates; (7) sulphoxides and sulphones; (8) hydroxyl amines or N-oxides; and (9) epoxides. It sometimes happens that compounds oxidized according to this invention are also pyrolyzed into lower homologues thereof. The term oxygen addition products is intended to also encompass such oxygenated lower homologues as may be produced by the practice of this invention.

It should be noted that this invention is adapted to use in the desulfurizati-on of petroleum fractions or crudes,

particularly such fractions which have little or no olefinic' unsaturation. The fraction to be desulfurized is mixed with vapor phase peracetic acid and the peracetic acid reacted therewith to convert sulfides to sulfoxidies and/or disulfides to sulfonic acids. The newly created materials, sulfoxides and sulfonic acids are much more readily separable from the remainder of the hydrocarbon portions of the petroleum fraction by conventionaldistillation and/ or extraction means than were their precursors.

This invention is also well adapted to producing N- oxides (amine oxides) by the reaction of amines with per acetic acid. These amine oxides are particularly useful in detergent formulations and as dyeing assistants. Amine oxides are prepared by oxidation of amines with peracetic acid according to any of the particular aspects set forth below. Thus, the particular process applicable to each particular amine will be determined in great measure by the boiling point of the particular amine and amine oxide under consideration. For example, methyl diphenyl amine has a boiling point above C. and, as set forth below, should be oxidized in a manner similar to soybean oil.

According to one aspect of this invention, oxidizable compounds, having boiling points higher than acetic acid which are oxidizable or epoxidizable to products having boiling points higher than acetic acid, are oxidized in a still-reactor by peracetic acid to such products. Oxidizable compounds treated in this aspect of this invention are generally those which are not readily distilled and are difficult to separate from oxygenated derivatives thereof by convenient distillation means. Thus in this aspect of this invention it is desirable that the reaction be driven to completion with respect to the oxidizable compound. To this end, it is desirable to provide a mole equivalent excess, on a reactive group basis, of peracetic acid. Thus it has been found desirable to provide an excess up to about 50% of peracetic acid when epoxidizing materials accord ing to this aspect of this invention. It is of course within the spirit and scope of this invention to utilize greater than 50% excess peracetic acid if desired, however such large excesses have not been found to improve the reaction process sufficient to warrant such use. In this aspect of this invention virtually all of the excess peracetic acid which does not react in the oxidizable compound comes out of the still-reactor as distillate and reacts with acetaldehyde upon condensation to form acetic acid which is a valuable by-product. Materials epoxidizable or oxidizable according to this aspect of this invention are those having boiling points above about 180 C. Representative compounds in this class include benzaldehyde, phenyl hydrazone, brassidic acid and esters thereof, tat-carotene, ,B-carotene, cholesterol, cholesteryl acetate, cholesteryl benzoate, cinnarnyl alcohol, citral, citronellal, citronellol, crotonic acid and esters thereof, diisobutylene, dihydronaphthalene, elaidic acid and esters thereof, erucic acid and esters thereof, ethyl acetoacetate, furfural diacetate, 2,6-dimethyl octadiene- 6-ol (2,6)indene, ot-ionone, ,B-ionone, itaconic acid and esters thereof, limonene, linoleic acid and esters thereof, linolenic acid and esters thereof, p-menthene-l, octadec ylene-l, oleic acid and esters thereof, pulegone, tetraphenyl ethylene, diphenyl sulfide, diphenyl disulfide, methionine, thianthrene, amino azobenzene, azobenzene, p-hydroxyazobenzene, chloroquinoline, dimethyl aniline, p-methoxy quinoline, methyl benzyl aniline, methyl di phenyl amine, naptho phenazine, phenanthrolines (o,m,p), phenazine, quinoline, quinoxaline, methyl vinyl carbinol, diallyl ether of Bisphenol A [2,2 bis (p,p','allyloxy)phenyl propane] and maleic acid and esters thereof.

In one specific embodiment of this aspect of this invention, soybean oil is epoxidized by introducing liquid soybean oil into a still-reactor near the top thereof; introducing peracetic acid containing vapor at an intermediate point in the still-reactor; taking a vaporous distillate from the still-reactor of at least acetic acid; partially condensin'g the distillate to remove liquid acetic acid therefrom; and recovering a liquid rafiinate of epoxidized soybean oil. In a preferred form of this embodiment, the vaporous distillate contains acetic acid and acetaldehyde and the distillate is partially condensed to provide liquid acetic acid and vaporous acetaldehyde. Where the peracetic acid containing vapor feed to the still-reactor is the product of vapor phase oxidation of acetaldehyde, the vapor product, acetaldehyde, of the partial condensation of the still-reactor distillate is recycled to the vapor phase acetaldehyde oxidation reaction. It is also Within the scope of this aspect of this invention to totally condense the still-reactor distillate and subsequently separate the acetic acid and acetaldehyde.

This embodiment is preferably carried out in a stillreactor operating at about 65 to 150 C. at a pressure of about 50 to 760 mm. Hg absolute with a contact time of about 30 seconds to 2 hours. It is preferred to utilize a continuous process with vaporous acetaldehyde and oxygen fed to an aluminum reactor in such concentration that the feed is preferably about 10% by weight oxygen or less. The reaction suitably proceeds at about 100 to 200 C. preferably 120 to 160 C. The oxidation reactor product, at a temperature of 120 to 160 C., is fed into a distillation column while liquid soybean oil or other similar oxidizable material is fed to a higher point on the same column at a temperature at 20 to 150 C. and at a feed rate of about 0.8 to 1 part by weight of oil per part of acetaldehyde feed. The vaporous distillate product is partially condensed and the liquid raffinate product is collected as set forth above.

Example I In one specific example of this particular embodiment, which is given by way of illustration without it in any way limiting this invention, acetaldehyde at 85 C. was fed into an aluminum reactor at a rate of 7.7 moles per hour admixed with an oxygen stream containing 5% nitrogen in a mole ratio of acetaldehyde to oxygen of to 1. Soybean oil was fed to the top plate of a 45-plate distillation column which column was operated at a temperature at 100 C. at 250 mm. Hg absolute pressure with the raffinate product conducted through a short stripper section (below the 45-plate column) operating at a temperature of 150 C. The Weight ratio of acetaldehyde feed (to the vapor phase oxidation reaction) to soybean oil feed was 3.2 to 1. The vapor phase oxidation product containing 12 Weight percent peracetic acid was fed in the vapor state below the bottom plate of the stripper section. The soybean oil reacted with the peracetic acid in the still to produce acetic acid and epoxidized soybean oil. The still-reactor raflinate was quickly cooled to room temperature as it came off from the base of the still-reactor and 107 parts by weight per hour of epoxidized soybean oil product containing 1.3% acetic acid was recovered. The acetic acid was removed by washing to yield a product containing 6.9 weight percent oxirane oxygen with an iodine number of 1.1 and a color of Gardner 1. The still-reactor distillate came off as a vapor from the top of the still at 100 C. and was passed through a Dry Ice-acetone trap to condense acetaldehyde and acetic acid while venting the permanent gasses.

In another specific embodiment of this aspect of this invention, esters of tall oil acid, such as 2-ethylhexyl tallate, are epoxidized by reacting tall oil ester with vaporous acetaldehyde oxidation product in a manner similar to that set forth above with respect to soybean oil. The reaction products are acetic acid and epoxidized tallate with acetaldehyde passing through the reaction system.

Example 11 In another specific example of this embodiment, acetaldehyde was oxidized with oxygen as set forth in Example I above to yield peracetic acid oxidation product containing vaporous acetaldehyde. 2-ethylhexylta1late was fed into a still-reactor identical to that described in Example I above at 25 C. in a weight ratio of acetaldehyde feed to tallate feed of 3 to 1. The still-reactor raffinate came off as a liquid at room temperature to yield 116 parts by weight per hour of epoxidized Z-ethylhexyltallatc containing 1.3% by weight acetic acid. The raffinate was washed to remove acetic acid yielding a product having an oxirane oxygen content of 5% by weight, an iodine number of 2 and a color of Gardner 1. The still-reactor distillate came off as a vapor at 100 C. and was condensed as set forth above in Example I.

Example III In another specific example of this embodiment, parts by Weight per hour of a solution of 34.5 weight percent peracetic acid in acetic acid was vaporized at a pressure of 250 mm. Hg absolute and fed into a still reactor similar to that described in Example I between the bottom tray of the 45-tray column and the stripper section. The column was maintained at C. Soybean oil was fed at 25 C. onto the top tray of the column at 69 parts by weight per hour. The epoxidized product was taken as a raffinate through the stripper section at C. and was recovered at 30 C. The yield was 72 parts by weight per hour of raffinate containing 3.8 weight percent acetic acid. The raffinate was washed with dilute potassium hydroxide solution to remove the acetic acid therefrom and the resultant epoxy product after drying had an oxirane oxygen content of 6.8 weight percent and an iodine number of 1. The column distillate was taken at a rate of 86 parts by weight per hour and was acetic acid containing 4.4% by weight peracetic acid.

Example IV A vapor mixture, similar to that used in Example I, containing 9.9 mole percent peracetic acid, 23.4 mole percent acetic acid, and 66.7 mole percent acetaldehyde was fed at a rate of 4.65 moles per hour into a still-reactor identical to that described in Example I, between the bottom plate and the short stripper section. 2,2-bis(p,p'- diallyloxyphenyl) propane was fed into the top of the still-reactor at a rate of 0.325 equivalent per hr. The still-reactor was maintained at 100 C. and 250 mm. Hg absolute. The epoxidized product was recovered as a raffinate which came through the stripper section of the still-reactor at 150 C., quickly cooled, and was taken from the system at 30 C. The yield was 55 parts by weight per hour of raffinate, which contained 5.7 wt. percent acetic acid, and which had an oxirane oxygen content of 4.3 wt. percent. The raflinate product was washed with dilute sodium hydroxide solution to remove the acetic acid and thus purify the product 2,2-bis(p-glycidylphenyl) propane. The distillate was taken overhead and condensed in Dry Ice-acetone cooled traps. The total distillate was 234 parts by weight per hour containing 137 parts by Weight per hour of acetaldehyde, 11 parts by weight per hour of peracetic acid, and 86 parts by weight per hour of acetic acid.

In another aspect of this invention, compounds having boiling points from about 125 to about C. are oxidized or epoxidized in a still-reactor by peracetic acid to an oxygenated derivative of the compound. Compounds treated according to this aspect of this invention are generally readily separable, by distillation techniques, from an oxygenated derivative thereof.

In this aspect of this invention it is convenient to recover any unreacted oxidizable compound and oxygenated derivative thereof as raffinate while taking acetic acid and acetaldehyde as vaporous distillate. The oxidizable compound in this aspect of this invention may suitably be maintained in the column by utilizing a high reflux or by providing a still-reactor with a large number of actual or theoretical plates or trays. Preferably acetic acid and acetaldehyde are refluxed overhead while the compound being processed is refluxed in the column. It is also preferred to provide the break point between the 9 acetic acid and the compound being processed a few plates down from the top of the column. The level of break point can be controlled by controlling the amount of acetic acid reflux.

Representative compounds processable according to this aspect of this invention include allyl propionate, camphene, dichloro ethylene, dicyclo penta-diene, l-dodecene, methyl crotonate, methyl cyclohexanone, nonene-2, octylene, pinene, styrene, stilbene (cis), d-ibenzyl sulfide, diallyl sulfide, ethyl n-butyl sulfide, 2,5-dimethyl pyrazine, 6-nitro quinoline, nitro styrene (o,m,p) and cyclohexanone.

Suitable reaction conditions for the oxidation or epoxidation of compounds according to this aspect of this invention with vaporous acetaldehyde oxidation product include a temperature of peracetic acid containing feed of 110 to 180 C.; a still reactor pressure of 100 to 760 mm. Hg absolute; oxidizable compound feed rate of 0.8 to 1.2 parts by weight per part of peracetic acid feed at about 25 to 150 C.; a distillate temperature of 80 to 150 C.; a partial condenser temperature of to 100 C.; and a rafiinate temperature of 150 to 250 C. The oxidizable compound and the oxygenated products thereof can be separated by distillation or solvent extraction.

Example V In another specific embodiment of this invention, a vapor mixture, similar to that used in Example I, containing 9.2 mole percent (13.4 wt. percent) peracetic acid, 29.2 mole percent (34.0 wt. percent).acetic acid, and 61.7 mole percent (52.6 wt. percent) acetaldehyde was fed at a rate of 1.85 moles per hour (95.2 parts by weight per hour) to the th plate from the bottom of a 50-plate column similar to that described in Example I. Cyclohexanone was fed to the 45th plate of the column at a rate of 0.71 mole per hour (70 parts by weight per hour). The column was operated at 100 C. and 135 mm. Hg absolute. Acetic acid, acetaldehyde, and a small amount of cyclohexanone were taken as a vaporous distillate through partial condensers maintained at C. whereby acetic acid, cyclohexanone, and acetaldehyde were recovered. The raflinate was taken from the column base (115 C.) at a rate of 64.5 parts by weight per hour and contained 47.7 parts by weight per hour cyclohexanone, 2.0 parts by weight per hour a-hydroxycyclohexanone and 14.8 parts by Weight per hour of e-caprolactone.

In still another aspect of this invention, compounds having boiling points at most about 125 C., and preferably above about C. are oxidized or expoxidized in a still-reactor by peracetic acid to an oxygenated derivative of the compound. Compounds treated according to this aspect of this invention are recovered as raffinate from the still-reactor in admixture with by-product acetic acid while any acetaldehyde which may be in the system is taken as a distillate overhead. To maintain the compound to be oxidized, and its oxidation product in the liquid phase, it is preferable to remove heat, as by heat exchangers external to each tray or by overhead reflux, during the reaction in the distillation system.

Representative compounds prooessible according to this aspect of this invention include allyl alcohol, diallyl ether, allyl chloride, caprylene, cycloheptene, cyclohexadiene, cyclohexene, cyclopentadiene, diallyl amine, pentene-l-Ol- 3, ethylvinyl ether, heptene-l, hexene-l, isoprene, methyl cyclohexene divinyl sulfide, S-n-itroquinoline, pyridine, and allyl acetate.

Example VI In one specific example of the practice of this aspect of this invention, glycidyl acetate was obtained by the epoxidation of allyl acetate. A mixture of peracctic acid (28.3 weight percent) and acetic acid (71.1 weight percent) were fed to the th plate from the bottom of a -plate stillreactor similar to that used in Example I at a rate of 62.4 parts by weight per hour (0.23 mole per hour of peracetic acid). Allyl acetate was fed to the 15th 'plate of the still-reactor at a rate of 53.4 parts by weight per hour (0.55 mole per hour). The still-reactor was operated at 155 mm. Hg absolute pressure giving a still-reactor temperature of 60-65 C. and a base temperature of 78 C. Vaporous peracetic acid was liquefied in contact with allyl acetate reacting therewith to form glycidyl acetate. The rafiinate was taken from the column base at a rate of 116 parts by weight per hour containing 33.4 parts by weight per hour of allyl acetate, 15.2 parts by weight per hour of glycidyl acetate, 7.3 parts by weight per hour of glycerine diacetate, 6.4 parts by weight per hour of glycerine triacetate, and 56.7 parts by weight of acetic acid.

According to another embodiment of this aspect of this invention, the epoxidation product of allyl acetate can be hydrolyzed to glycerine. In fact, this invention encompasses the process of converting propylene glycol diacetate to glycerine and other similar reactions.

Thus, propylene glycol diacetate is readily pyrolyzed to allylacetate, which is then epoxidized with peracet-ic acid to glycidyl acetate, followed by hydrolysis of the epoxidation product to glycerine with acetic acid by-pr0d not being recovered. The epoxidation product of allyl acetate is introduced into contact with 1.6 times its weight of water at C. which water is 0.01 N in sulfuric acid, in order to hydrolyze the epoxi-dation product to glycerine. The hydrolysis product is subjected to distillation or other separation techniques to remove the acetic acid therefrom and thus recover glycerine.

In any or all of the aspects of this invention, it is desirable to obtain maximum utilization of peracetic acid as an oxidizing agent. In order to accomplish this, it is desirable to prevent the non-productive decomposition of peracetic acid e.g. by catalysis or thermal degradation. Certain contaminants, e.g, iron, chromium, manganese, copper, and nickel should either be excluded from the system described herein, inhibited, sequestered or in some other way prevented from catalyzing the degradation of peracetic acid. It has been found particularly effective to use aluminum as the material of construction in which this process is carried out. Of particular value for use as a construction material in this invention is grade 6061 aluminum which is a normal structural grade aluminum free of copper, manganese, cobalt, iron, nickel and other heavy metals and which is structurally strong. If possible, it is preferred to use pure aluminum as the construction material for the practice of this invention.

While this invention has been described with reference to the use of peracetic acid as an epoxidizing agent and with reference to the manufacture of peracetic acid, it should be understood that other per carboxylic acids, e.g. perpropionic acid, are also useful in this invention.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. In an oxygen addition process wherein peracetic acid provided by the vapor phase oxidation of acetaldehyde is the oxidizing agent, the improvement wherein peracetic acid in admixture with acetaldehyde, in vapor phase, is brought together in a reactor and is contacted in the vapor phase with a liquid to be oxidized by oxygen addition.

2. The process of claim 1 wherein said liquid has a boiling point above 180 C.

3. The process of claim 1 wherein said liquid has a boiling point between C. and C.

4. The process of claim 1 wherein said liquid has a boiling point below 130 C.

5. In an oxygen addition process wherein peracetic acid is the oxidizing agent, the improvement wherein peracetic acid, in admixture with acetaldehyde, in the vapor phase, is brought together in a reactor and is contacted in the vapor phase with liquid soybean oil, and

said liquid soybean oil is oxidized by oxygen addition.

6. The process which comprises oxidizing vaporous acetaldehyde with oxygen at about 130 to 180 C. in an aluminum reactor at super-atmospheric pressure to a vapor product comprising peracetic acid and acetaldehyde; contacting said vapor product in the vapor state with an oxidizable material reactive with peracetic acid in an aluminum still-reactor having about 3 to 60 plates at a temperature of about 60 to 150 C. at a pressure of about 50 mm. Hg absolute to atmospheric; reacting said peracetic acid with said oxidizable material to form acetic acid and at least one oxygen addition product of said material; recovering at least said oxygen addition product as a ratfinate; and recovering at least acetaldehyde as a distillate.

7. The process claimed in claim 6 including reacting said peracetic acid with said oxidizable material in said still-reactor at about 100 C.; passing said raffinate through a stripping section at about 150 C.; separating said oxygen addition product from said rafiinate; partially condensing said distillate at a temperature between the boiling points of acetic acid and acetaldehyde; recovering acetic acid from said condensed distillate; and recycling vaporous acetaldehyde from said distillate to said acetaldehyde oxidation.

8. The process claimed in claim 7 including absorbing peracetic acid into said oxidizable material and then reacting said peracetic acid with said oxidizable material.

9. The process claimed in claim. 8 wherein said oxidizable material is soybean oil and said oxygen addition 30 product is epoxidized soybean oil. i

10. The process of claim 1 wherein said liquid is one selected from the group consisting of cyclic ketones, tall oil acid esters, unsaturated ethers, and allyl acetate.

References Cited by the Examiner UNITED STATES PATENTS 1,972,102 9/1934 Malisoif 208-219 2,314,385 3/1943 Bludworth 260530 2,377,038 5/1945 Reichert et al 260502 2,653,161 9/1953 Ballard et al. 260461 2,754,252 7/1956 Becker 208--219 2,785,185 3/1957 Phillips et al. 260348.5 2,802,025 8/1957 Weitbrecht et al. 260502 2,882,320 4/1959 Cheney et a1 260586 2,883,425 4/1959 Kealy 260586 2,972,631 2/1961 Bain et al. 260-563 2,986,570 5/1961 Monroe et al. 260348 3,018,294 1/1962 Phillips et a1 260348 3,053,856 9/1962 Payne et al. 260502 3,064,052 11/1962 Goldberg et al. 260563 3,072,703 1/1963 Turbak 260461 3,155,638 11/1964 Mueller et al 260784 FOREIGN PATENTS 634,234 1/1962 Canada. 1,298,157 10/1961 France. 1,127,342 4/ 1962 Germany.

547,333 8/1942 Great Britain.

832,337 4/1960 Great Britain.

OTHER REFERENCES Lee et al.: Epoxy Resins, McGraw-Hill Book C0., page 16 relied on (1957).

LEON J. BERCOVITZ, Primary Examiner.

ALFONSO D. SULLIVAN, Examiner.

S. P. JONES, F. MCKELVEY, Assistant Examiners. 

1. IN AN OXYGEN ADDITION PROCESS WHEREIN PERACETIC ACID PROVIDED BY THE VAPOR PHASE OXIDATION OF ACETALDEHYDE IS THE OXIDIZING AGENT, THE IMPROVEMENT WHEREIN PERACETIC ACID IN ADMIXTURE WITH ACETALDEHYDE, IN VAPOR PHASE, IN BROUGHT TOGETHER IN A REACTOR AND IS CONTACTED IN THE VAPOR PHASE WITH A LIQUID TO BE OXIDIZED BY OXYGEN ADDITION. 